Origin of mafic and ultramafic cumulates from the Ditrău Alkaline Massif, Romania
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Tartalom: http://dx.doi.org/10.1016/j.lithos.2015.09.022
Archívum: MTA Könyvtár
Gyűjtemény: Status = Published



Type = Article
Cím:
Origin of mafic and ultramafic cumulates from the Ditrău Alkaline Massif, Romania
Létrehozó:
Pál-Molnár, Elemér
Batki, Anikó
Almási, Enikő
Kiss, Balázs
Upton, Brian G.J.
Markl, Gregor
Odling, Nicholas
Harangi, Szabolcs
Dátum:
2015-10-08
Téma:
QE Geology / földtudományok
QE02 Geochemistry / geokémia
QE06 Petrology. Petrography / kőzettan, petrográfia
Tartalmi leírás:
Mafic?ultramafic cumulates enclosed in gabbroic-dioritic rocks form part of the Mesozoic Ditr?u Alkaline Massif
in the Eastern Carpathians, Romania. The poikilitic olivine- and pyroxene-rich and nearly mono mineralic
hornblendite rocks display typical cumulate textures with early crystallised olivine (Fo75?73), diopside and augite. In the early stages of their genesis the amphibole was intercumulus whilst in later stages it acquired cumulus status as the fractionating magma evolved. Using major and trace element compositions of minerals and whole-rock samples the origin of these cumulates is determined and the parental magma composition and depth of emplacement
are calculated.
Cumulus clinopyroxene has more primitive composition than intercumulus amphibole suggesting closed system
fractionation for the evolution of poikilitic olivine- and pyroxene-rich cumulates. The evolution of the amphibole-rich mesocumulates is more clearly the result of closed system crystallisation dominated by the precipitation of clinopyroxene and amphibole cumulus crystals.
Lamprophyre dykes of the Ditr?u Alkaline Massif are proposed to reflect multiple basanitic parental magma
batches from which the cumulus olivine and clinopyroxene crystallised. Relative to these dykes the calculated
equilibrium melts for intercumulus amphibole in the cumulates was more primitive whilst that for the cumulus
amphibole was more evolved. The calculated crystallisation temperature and pressure of ~1000?1050 °C and ~0.7 GPa, based on the composition of the amphiboles, indicate crystallisation at lower crustal depths. Rare
earth element compositions are consistent with an intra-plate tectonic setting.
Típus:
Article
PeerReviewed
Formátum:
text
text
Azonosító:
Pál-Molnár, Elemér and Batki, Anikó and Almási, Enikő and Kiss, Balázs and Upton, Brian G.J. and Markl, Gregor and Odling, Nicholas and Harangi, Szabolcs (2015) Origin of mafic and ultramafic cumulates from the Ditrău Alkaline Massif, Romania. Lithos, 239. pp. 1-18. ISSN 0024-4937
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